The present invention generally relates to apparatus and methods for electrical testing of circuits generally and more particularly to apparatus and methods for suitable for fixtureless electrical testing of electrical circuits.
There exist a wide variety of apparatus for electrical testing of electrical circuits. These apparatus include non-contact systems such as electron beam, laser plasma and electrical field testers, and contact systems such as bed-of-nails and flying probe testers. Conventional apparatus for electrical testing of electrical circuits suffer from one or more of the following drawbacks: high cost of operation, high set-up cost for different circuit board configurations, slow speed, inability to accurately and detect, in a repeatable fashion, various types of defects in electrical circuits under test.
The present invention seeks to provide improved apparatus and methods for fixtureless electrical testing of electrical circuits.
In accordance with a general aspect of the invention there is provided at least one electrical testing array comprising at least two electrical testing probes. Each probe is configured to be selectively positionable and to engage selected portions of an electrical circuit board. At selected points of engagement, electrical characteristics of the selected electrical circuits are sensed.
Embodiments of the present invention include one or more of the following additional features:
At least some of the probes include a static probe assembly, located in a fixed position in an array of probe assemblies, and a selectively positionable probe element.
At least some, and preferably all, positionable probe elements are independently positionable relative to other probe elements.
Each probe element is operative to engage a portion of the electrical circuit located within a region of engagement, and the respective regions of engagement of adjacent probe elements at least partially overlap.
Each probe element is each operative to engage a portion of the electrical circuit located within a region of engagement, and the respective regions of engagement of non-adjacent probe elements generally do not overlap.
Control circuitry is provided to position each of the probe elements so as to provide a selectively configurable electrical testing pattern.
The control circuitry is operative to move at least some of the probe elements, while at the same time, other probe elements are held in position for sensing an electrical characteristic of an electrical circuit on an electrical circuit board to be tested.
The control circuitry is operative to position the probe elements into a sequence of different electrical testing patterns, and to test different parts of an electrical circuit on an electrical circuit board to be tested when the probe elements are in each of the various electrical testing patterns.
First and second testing arrays, each comprising probe elements, are respectively provided along each side of an electrical circuit board to be tested, and a testing pattern includes probe elements suitably positioned along both sides of the electrical circuit to sense a characteristic of an electrical circuit that passes through the electrical circuit board to be tested.
First and second testing arrays, each comprising probe elements, are respectively provided along each side of an electrical circuit board to be tested, and the probe elements are sequentially positioned into a sequence of testing patterns, each testing pattern including probe elements suitably positioned along both sides of the electrical circuit, to sequentially sense a characteristic of different parts of an electrical circuit that passes through the electrical circuit board to be tested.
The probe elements are contact probe elements operative to engage selected electrical circuits by physical contact. Alternatively the probe elements may be non-contact probe elements operative to electrically engage selected electrical circuits, without physical contact, for example, by plasma.
In accordance with an additional general aspect of the invention, a method for electrically testing electrical circuits includes sensing electrical characteristics of portions of electrical circuits to be tested by selectively engaging the portions to be tested with probes that are each associated with a static probe assembly arranged in a fixed array of static probe assemblies. The probes are each independently positionable within a region that partially overlaps the corresponding region of an adjacent probe assembly, and that generally does not overlap the corresponding region of a non-adjacent probe assembly.
In accordance with an additional general aspect of the invention, a method for manufacturing electrical circuits includes depositing a pattern of electrical circuit conductors on a multi-layered substrate, and testing an electrical characteristic of selected portions of the electrical circuit using a multiplicity of static probe assemblies which are located in a fixed array of probe assemblies and which each have an independently positionable probe element.